Fix test_image_overlay for py27
Fix test_image_overlay for py27

talespaiva/folium,shankari/folium,shankari/folium,python-visualization/folium,python-visualization/folium,ocefpaf/folium,QuLogic/folium,QuLogic/folium,talespaiva/folium,talespaiva/folium,QuLogic/folium,talespaiva/folium,shankari/folium,ocefpaf/folium